Browser bar problem - virus?

When I type in the URL bar or seach bar, the system starts to generate ——————————————————————. It is happening with ie and firefox. I have norton antivirus and today ran Malwarebyte - no problems show up. If is shut down the laptop and restart the problem disappears for a while. Using Windows xp - Problem started yesterday. Thanks!

Perform a clean startup to determine whether background programs are causing the problem.